RESUMO Foram estudadas 135 vacas mestiças, provenientes de 10 rebanhos leiteiros no estado do Acre. O objetivo foi identificar espécies de Staphylococcus isoladas dos quartos mamários de vacas com mastite e, posteriormente, avaliar a capacidade de produção de biofilme pela espécie Staphylococcus chromogenes. A caracterização dos isolados presentes nas amostras encontradas, correspondentes a Staphylococcus sp., foi realizada utilizando-se a técnica do MALDI TOF MS (Matrix Associated Laser Desorption-Ionization - Time of Flight - Mass Spectrometry). Foram identificados: S. chromogenes (36), Staphylococcus saprophyticus (5), S. chromogenes ou Staphylococcus hycus (5), Staphylococcus haemolyticus (4), Staphylococcus epidermidis (3), Staphylococcus hycus (3), Staphylococcus aureus (1), Staphylococcus auriculares (1), Staphylococcus kloosii (1) e Staphylococcus xylosus (1). A espécie S. chromogenes correspondeu a 60% dos isolados do gênero (17 isolados coagularam o plasma de coelho no teste da coagulase em tubo), sendo 83,3% dos isolados (30/36) produtores de biofilme, não estando esse fator de virulência associado ao fenótipo de coagulação do plasma. A identificação desses microrganismos é importante para a elucidação da etiologia da mastite bovina. O alto percentual de S. chromogenes, produtores de biofilme, isolados de vacas com mastite é um achado relevante e pode revelar uma mudança de perfil na colonização de agentes etiológicos causadores dessa enfermidade.
Staphylococcus species are important pathogens associated to mastitis in lactating cows. Among coagulase‐negative staphylococci, Staphylococcus chromogenes is one of the most prevalent. However, most of the virulence and antimicrobial resistance studies have been done to Staphylococcus aureus isolates. Therefore, the aim of present study was to determine the antimicrobial susceptibility profile of biofilm producing S. chromogenes isolates recovered from cows with mastitis from the Northern region of Brazil. Of one hundred thirty‐five crossbred cows from ten dairy farms with milk production decline, sixty‐seven were with mastitis according to mammary gland clinical examination or California Mastitis Test. Milk samples were collected of these animals to microbiological analysis. Phenotypic tests and MALDI‐TOF were adopted for the bacterial identification. Most of the staphylococci isolates (n=36; 60%) was identified as S. chromogenes. Absorbance‐based method was carried out to determine quantitatively the biofilm production by isolates of this species. Fifteen isolates, with different biofilm production levels, were submitted to the disk diffusion method to ceftiofur, clindamycin, chloramphenicol, ciprofloxacin, enrofloxacin, erythromycin, gentamicin, linezolid, penicillin G, rifampicin, streptomycin and tetracycline. All isolates were susceptible to gentamicin, linezolid and rifampicin. The majority of the isolates were non‐susceptible to penicillin G (n=10; 66.7%), ceftiofur (n=9; 60%), clindamycin (n=9; 60%), enrofloxacin (n=9; 60%) and chloramphenicol (n=8; 53.3%). Multidrug resistance (MDR) was observed to 60% of the isolates. The non biofilm producing isolates (n=3) were susceptible for all antimicrobials, except one was resistance only to penicillin G. MDR was observed among the isolates independently of the biofilm production level (weak, moderate or strong). Isolates susceptible for all antimicrobial agents were also detected among strong and weak biofilm producers. Although few S. chromogenes isolates have been analyzed, high rate of MDR was observed in the present study. Besides antimicrobial resistance these isolates are biofilm producers that is an important virulence strategy. The MDR rate observed may be related to spread of the same strain among the cows of the herds studied. Most studies should be made to this Staphylococcus species due its importance in dairy herds. Moreover, it may contribute to resistance dissemination among other bacterial species, including those of impact in public health, as one source of these genes.Support or Funding InformationDevelopment Agency: Conselho Nacional de Desenvolvimento Científico e Tecnológico‐CNPq, Fundação de Amparo à Pesquisa do Estado do Acre ‐ FAPAC.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
This study aimed to identify the Staphylococcus species responsible for bovine mastitis in dairy herds in northern Brazil, to investigate the capacity of biofilm production, and to analyze the association of biofilm production with multiresistance and intensity of California Mastitis Tests (CMT) reactions that can make treatment more difficult and cause misdiagnoses, respectively. Milk samples were collected from 23 dairy farms located in five municipalities in the state of Acre. A total of 339 crossbred cows were tested by CMT, with 109 animals (229 udder ceilings) reacting to the test. After bacterial isolation in blood agar, the catalase-positive and gram-positive cocci were submitted for identification by MALDI-TOF MS. Of 103 strains identified as staphylococci, Staphylococcus chromogenes (58.3%) and Staphylococcus aureus (19.4%) were the most prevalent species. Biofilm production was quantitatively evaluated using a microplate adherence test. Among the Staphylococcus strains, 71.8% were biofilm producers. Most strains of S. chromogenes (68.3%) had the capacity to produce biofilms, ranging from weak (43.3%), moderate (13.3%), and strong (11.7%) producers. Among S. aureus strains, 50% were non-biofilm producers, and none were strong producers. Our data showed an association between biofilm production capacity and multidrug resistance. In addition, there was a reduction in the response to the CMT test, which can mask the diagnosis.
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